Oil pressure controller for pipe-type electric cable



J. L. LANSCH OIL PRESSURE CONTROLLER FOR PIPE-TYPE ELECTRIC CABLE 9Sheets-Sheet 1 Nov. 3, 1964 Filed July 25, 1960 m. an

Nov; 3, 1964 J. L. LANSCH 3,155,755

I OIL PRESSURE CONTROLLER FOR PIPE-TYPE ELECTRIC CABLE Filed July 25,1960 9 Sheets-Sheet 3 INVENTOR.

Joy/v z. M/vsch' Nov. 3, 1964 J. L. LANscH 3,155,755 OIL PRESSURECONTROLLER FOR PIPE-TYPE ELECTRIC CABLE Filed July 25, 1960 v 9Sheets-Sheet 4 lam/1.441150 Nov. 3, 1964 J. L. LANSCH. 3,155,755

OIL PRESSURE CONTROLLER FOR PIPE-TYPE ELECTRIC CABLE Filed July 25, 19609 Sheets-Sheet 5 INVENIOR.

J'o/l/v L zA/vsa/ wwk HIS AGENT J. LANSCH 3,155,765 on. PRESSURECONTROLLER FOR PIPE-TYPE ELECTRIC CABLE Nov. 3, 1964 i m Q m mvv Nov. 3,1964 J. L. LANSCH 3,155,765

OIL PRESSURE CONTROLLER FOR PIPE-TYPE ELECTRIC CABLE Filed July 25, 19609 Sheets-Sheet 7 484 r 483 RECORDER MOTOR STARTER PANELl22,l26,l34,|4l,l42

,3n igb) TIMER TERMINAL BLOCK 4? 49, 66

TERMINAL BLOCK CONTROL PANEL 47' megazngeqgggg 469 L ALARM PANEL 299,sol-502503304505 306507308309 5 INVENTOR.

JOHN L. LANSCH W M Nov. 3, 1964 J. L. LANSCH 3,155,765

on. PRESSURE CONTROLLER FOR PIPE-TYPE ELECTRIC CABLE Filed July 25, 19609 Sheets-Sheet 8 v 62! v f 94 6% e s e 39 ge 6 225 @feu @636 @657 5658$659 $641 $642 @643.

Fig. 7

INVENTUR J. L LA NSCH United States Patent 3,555,765 @IL PRESSURECQN'IRQLIJER FQR PEPE-TYPE ELECTRIC (TABLE Io'nu L. Lansch, Nyaclt, NY,assignor, by mesne assignments, to Anaconda Wire and Cable Company, acorporation of Delaware Filed .luly 25, 1969, Ser. No. 45,115 8 Claims.(Cl. 174-11) My invention relates to apparatus for maintaining oilpressure in a pipe-type cable system and particularly to such apparatusincorporating automatic switch-over devices responsive to failures inthe electric or hydraulic components of the system.

In pipe-type cables electrical conductors insulated for high voltageservice, by which I means service at voltages usually above kv. and ashigh or higher than 230 lrv., are laid in a fluid-tight pipe which iskept filled with electrical insulating rade oil under pressure. Theinsulation used for pipe-type cable is almost universally a plurality oflayers of paper which is penetrated by the insulating oil. To achieveadequate dielectric strength while the cable is energized the insulatingoil is maintained at a high pressure which has become standardized atabout 200 p.s.i.g. To maintain the purity of the oil it is also highlydesirable to maintain positive pressure in the line at all times eventhough the cable is inoperative. This pressure need not be as high asthe pressure maintained around the conductors when they are energizedand I prefer to keep a pressure of about 60 p.s.-i.g. on the cable whenit is deenergized.

A pipe-type cable is usually an expensive engineering installationsupplying power to important industrial and utility systems where anyinterruption of service will involve large economic losses. I havetherefore incorporated in my apparatus alarms and automatic safeguardsto prevent minor irregularities in the system from progressing to thepoint of :a power shutdown.

During normal operation of a pipe-type cable the oil in the pipe willexpand and contract periodically and provision must be made to store theexcess oil during periods or" expansion, and to maintain adequatepressure during periods of contraction. The oil expands because it isheated either by transfer of heat from the electrical conductors whenthey are under load, or by transfer of heat through the pipe from theoutside surroundings.

To accommodate the excess oil during periods of expansion I haveprovided one or more reservoirs or tanks connected by means of a novelcombination of piping and check valves, and mechanical and magneticrelief valves to the pipe-type cable. To maintain pressure in thepipe-type cable during periods of contraction of the oil I have providedone or more controllers, each incorporating a pump for returning oilfrom the reservoir into a pipe-type cable. Although I prefer to usepumps to build up oil pressure it will be understood that other pressuremeans such as pressure supplied from gas cylinders, may also be used.

I have provided a novel combination of controls and local and remotealarms said controls and alarms being controlled by a plurality ofrelays. Said relays, in my invention, are of an interchangeable, plug-intype whereby any relay failure may be immediately corrected by theinserti .1 of a spare relay for which I have provided a specialreceptacle to replace the faulty member. I have also provided a novelbuilt-in means for testing the circuitry of my apparatus withoutinteirupting the operation thereof and without setting oh any remotefalse alarms.

I have provided my apparatus with means whereby when a plurality ofpumps are used, failure or inadequacy of one pump to maintain pressurein an associated portion of the system will automatically openconnectors to the output from an adjacent pump and I have also providedthat this automatic cross over shall take place only during operation ofthe pipe-type cable at normal pressure.

I have provided my apparatus with a novel combination of mechanical andmagnetic relief valves whereby I am able to control the pressure in apipe-type cable within much closer limits than has heretofore beenpracticable.

I have provided my system with means whereby upon failure of a normalsource of power the apparatus will switch over to an auxiliary source,and I have also provided that such momentary interruptions of powershall not set oil any remote alarms and that following a powerinterruption the system shall automatically resume a type of operationwhereby it maintains the pipe-type cable at normal pressure.

Prior art devices for regulating the pressure in pipe-type cables haveinvolved separate and distinct systems for control and for alarm. In mysystem there is a close integration of the alarm and control functionwhereby the same relay that operates a control valve or other mechanismis interlocked with alarm circuits when necessary.

My system comprises novel interlocking circuitry whereby only certainsequencies of operations which may be known only to selected authorizedpersons may be followed to change to reduced pressure operation or tochange from manual to automatic controls.

I have further provided that connection between the operating elementsof my system and the control panel shall be made by means of a pluralityof plugs and matching receptacles whereby it is possible to isolatesections of the system for the purpose of making changes or repairs. Inaddition I have provided an interlock which will show an alarm when anyof the aforementioned plugs are not connected to their receptacles.

Means are provided in my apparatus to maintain pumping actions untilpressure has risen at the remote ends of the pipe-type cable and to showan alarm for excessive cycling or failure of pumping action to reach therequired pressure within a reasonable time.

I have incorporated in my system novel means for simultaneously testingall the signal lamps including the lamps in the control circuits withoutat the same time interrupting the normal operation of my apparatus.

Further advantages and objects of my invention will be made apparent byconsideration of the appended drawings and the detailed descriptionsthereof.

In the drawings:

FIG. 1 is a schematic diagram of the apparatus and piping of oneembodiment of my invention.

FIG. 2 is a wiring diagram of the power transfer switch of oneembodiment of my invention.

FIG. 3 is a wiring diagram of the main power circuit breaker and motorstarter for the pump of my invention.

FIGS. 4a and 4b combined are a wiring diagram of a portion of theapparatus of my invention.

FIGS. 5a and 51) combined are a wiring diagram of another portion of theapparatus of my invention.

FIG. 6 is a block diagram of a feature of my invention.

FIG. 7 is a perspective view of a test unit of my invention.

FIG. 8 is a wiring diagram of a test unit of my inventio-n.

Referring to FIGURE 1 twin controllers designated generally 11, Ila,mounting high pressure pumps 13, 13a are connected through pipe lines14, 14a to a pipe-type cable, not shown, within which it is desired tomaintain ii at an elevated pressure, such as a pressure of 200 p.s.i.g.It is required that this pressure shall be maintained in the systemwithin a narrow range notwithstanding changes in temperature causingexpansion and contraction in the oil, or slow leaks or seepage of oilfrom the system. It is also required that appropriate alarms be given atthe controllers and possibly at one or arsavse more remote stations inthe event of a large leak or of loss of power to the pumps 13, 13a orother emergencies as shall be hereinafter described.

I have shown the twin controllers ll, lla associated with pipe lines14-, l ia but a single controller such as lla may be used for apipe-type cable system not large enough to require twin controllers.Where twin controllers are used they may be installed at a joint in arelatively long pipe-type cable with the pipe line 14 connected to thepipe-type cable on one side of the joint and the pipe line lea connectedto the same pipe-type cable at the other side of the joint.

The pipe lines and 14a for which I prefer to use 2-inch steel pipe, arejoined at a normally closed manual stop valve 15 and flow through thelines can be controlled by a pair of normally open manual valves 15, 16adownstream and 17, 17a upstream of a pair of cross couplings 28, 18a. Apair of normally closed manual valves 19, 1% each seal off one leg ofthe cross couplings 18, 13a affording provision for possible futureconnections.

I prefer to assemble certain valves and other equipment to be describedin a trench 259 from which pipe connections are made to the controllersll, Illa through G-ring sealed unions 2i, Zla, 22 and 23, 23a.

The upstream sides of the valves 17, 17a are joined through Ts 24, 24aand the unions .22, 22a to the pipe lines as, 2-6:; controlled bynormaly open manual stop valves 27, 2711. Within the trench ill I havelaid the pipe lines 28, 28a connecting respectively, the Ts 2d, 2442 tothe unions 23, 23a. heck valves Z9, 2% in lines 28, 28a prevent flow insaid lines back from the Ts 24, 24a.

Connecting the pipe lines 23, 28a, I have placed a crossover systemcomprising check valves 31 and 32 normally closed magnetic relief valves33 and 34 and normally open manual stop valves and 37; also in thetrench 2i) 1 have included a pipe line 33, connected to the oil storagereservoir system generally designated by the numeral 39. The line 38, isconnected to the controllers ll, Illa through the unions 21, Ziarespectively under the control of normally open manual stop valves 4-1,lla. Entry to an oil storage tank 42 takes place through two Ts 43, 43ain the pipe lines 38, isolated by a normally closed stop valve Entryinto the tank -2 is further controlled by normally open manual stopvalves as,

The oil tank 42 is equipped with oil level indicator alarm i? and an oildrain controlled by a normally closed manual stop valve A ther 'lOS'EEli49 has been located on. the controller ill but may be placed at anyconvenient location in the pump room. A cylinder 5d of dry inert gas ofwhich nitrogen is a preferred example provides an inert atmosphere tothe tank 42. through the pipe line 51 having normally open manual stopvalves 52, 53, 5dand 56. The pipe line El for which I prefer to usehalf-inch copper piping is connected to a safety vent 57 through anormally closed manual stop valve 58. The vent 57 is connected to theoil tank 42 through a safety head diaphram 59. A manhole 611. providesentrance to the 42 for the purpose of cleaning.

The cylinder St) is equipped with a regulator 62 cor1- nected by meansof the flexible hose 63 and normally open manual stop valve 64 to thepipe line 51. The valve 56 is located in the controller lllzz Which alsocontains a pressure alarm 66 and pressure gauge 67 connected to the pipeline 51. Oil leaving the tank 42 enters through the pipe lines 38, 33aand the unions 21, Zita through normally open manual stop valves 63,otia into the pumps 13, 513a. The pumps 13, 13a force the oil from thestorage tank 42 through check valves 69, 69a normally open manual stopvalves Fl, 71a and 72, 72a and the valves 29, 2%, 17, 17a and lo, l ainto the pipe-type cable.

A return oil circuit between the tank 42 and the pipetype cable isprovided through the pipe line 14, the valves 16, 16a, the crosscouplings i3, 136! valves 17, 17a, the Ts 24, 24a, the unions 22, 22a,the valves 2-7, 270, the pipelines a6, 2601, the Ts 73, 73a, 74, 74a,rs, 76a, '77, 77a through strainers 73, 78a, normally open magneticrelief valves '79, 79a, normally closed mechanical relief valves bl,81a, normally open manual stop valves 82, 82a, Ts 83, 33a, 84, fida, as,boa, normally open manual stop valves b7, 37a, the unions 21, 21a, thepipe lines 33, 3&1, the valves 41, Alla and 46, 45a. The valves 31, 81aare closed until the pressure in the oil reaches some predeterminedvalue which I prefer should be 225 p.s1.g.

A pair of valves parallel to the valves ill, 81a and 32, 82a areprovided by normally closed mechanical relief valves 8%, 855a andnormally open manual stop valves 89, 3911. I prefer to have the valves33, 83a set to open at a pressure at 250 p.s.i.g'. Valves i l 93a arenormally closed manual valves closing a circuit parallel to the circuitsprovided through the valves til, 82, lla; 82a) and 88, 39 (38a; 89a).Parallel to the lines comprising respectively the strainers 7%, Ida, thevalves 83, 88a, 79, 7%, $1, 31a, 35*, 83a and 22., 82a are linesconnected to the Ts 74, 7 m including normally closed m agnetic reliefvalves @l, la, check valves 92, 92a, and normally open manual stopvalves 93, 93a. The magenetic relief valves 91, la are automaticallyopened at a predetermined pressure which I prefer should be 300 psig. bymeans of a control circuit hereinafter to be described.

From the foregoing it will be evident that the mechanical valves 81,hla, 8%, 88a and the magnetic valves 91, 91a provide stepped means forrelieving pressure transmitted from the pipe-type cable to the pipelines M, Ma by releasing oil into the tank A further safeguard comprisesbuilt-in spring-loaded relief valves 95, @561 in the pumps 13, I preferto use valves which Will release When the pressure in the pumps reachesa value of 375 p,s.i.v.

The controllers ll, Illa contain oil pressure recorder and control units94, 94a for which I prefer to use Foxboro Standard Recorders with dualrotaX units such as number 77 SD X 77-779 special for 24- volt DC.service, supplied by the Foxboro Company.

Each of the units 94, 9411 includes two pressure actuated contactdevices hereinafter to be described. The left hand of said devices isconnected through the pressure piping @6, 96a normally open instrumentstop valves 97, 97a, @8 and 98a, unions 22 22a, Ts 24, 24a and pipelines 14, 14a to the pipe-type cable. On the same pipe lines 96, 96aseparated by normally open instrument stop valves 99, 99a are oilpressure gauges lllll, ltlla. It will be seen that the pressure in theleft hand devices of the units 94, 94in and in the oil pressure gaugesllll, ltlla being approximately equal to the pressure in the pipetypecable, the left hand devices may be used to actuate the automaticcontrols for the cable system.

The right hand devices of the units 94-, 94a are connected throughpressure piping lll2, lllZa normally open instrument stop valves W3,1103a and Jill-l, ltlda to the discharge side of the pumps 13, 3 13a.Normally closed instrument stop valves res, 106a separate the left handpiping 96, %a from the right hand piping 162, lllZa. The right handdevices are used to control the pumps 13, 15a.

In the event of damage to either of the pumps 13, or 1301 said pumps canbe isolated by closing the respective valves 68, 68a Without interferingwith the operation of the automatic controls actuated by oil pressure inthe piping 96, 96a.

The piping of the controllers ll, lla is interrelated in the mannerhereinbefore described, the circuitry of the controller ll ispractically identical to the circuitry of controller llla, so that theoperation of only controller ll Will be described, with theunderstanding that the operation of controller 11a is, for the purposeof this application, practically identical.

Referring to FIGURE 2, power for the operation of the controller 11 andauxiliary equipment is received from a S-phase normal supply syste lllwhich may conven iently be 208 volts phase-to-phase but may have othervoltage values such as 220, 230, 240 and 440 volts. Power for theoperation of my system can also be received from an emergency supply 112having the same characteristics as the normal supply 111. Power from thenormal supply M1 is fed to a main circuit breaker 113 through a 3-polemagnetic switch 114 actuated by a coil 11 6. Power from the emergencysupply 112 is fed to the main circuit breaker 113 through a 3-polemagnetic switch 117 actuated by a coil 1?.8. Switches 114 and ll? aremechanically interlocked by a known mechanism indicated by the dashedline H5 in such a manner that both the switches lid and 117 may be openat the same time, either may be open with the other closed, but both ofthe switches Ill-.4 and El? cannot be closed at the same time.

A 4-pole transfer relay 19 is actuated by a coil 121. The relay 119comprises two normally closed switches 122, 123 and two normally openswitches 12 5, 12s.

The normally closed switch 122 of the relay 119 has one terminalconnected with a terminal of the normally open switch 125. The normallyopen switch I124 has one terminal connected through the coil 116 with aphase 127 of the normal supply llll. The other terminal or" the switch1124 is connected with a phase 128 of the normal supply llll and is alsoconnected through the coil I21 with the phase 127 of the normal supply111. One terminal of the switch 123 is connected through an on-oilswitch 129 through the coil 118 with a phase 131 of the emergency supplyH2. The other terminal of the switch 123 is connected with a phase 132or the emergency supply 112. From the foregoing it will be apparent thatwhen the normal power supply is energized current will pass through thecoil 121 closing the switches 124, 126 which in turn will activate thecoil 116 closing the power switch Zilld so that the current from thenormal supply can flow to the main circuit breaker 113. In the event offailure of the normal supply 111 the relay 11% will act to close theswitch 123 thus energizing the coil T113 and closing the switch 117 tosupply current from the emergency supply 112 to the main circuit breakerI13.

I have shown the normal power supply 111 and the emergency power supply112 for my controller ll. It is advantageous to wire my controller Ilain such a manner that it will employ the supply 112 as a normal supplyand the supply Jill as an emergency supply. Thus a dual controllersystem will in normal circumstances draw power from each of two sourcesof supply but continue to operate both controllers in the event of thefailure of either source.

The pump 13 (FIGS. 1 and 3) receives power through a magnetic motorstarter 133 (FIG. 3) actuated by the coil 134, which is in series withoverload switches 136. The starter 133 comprises, in addition to thethree phasecurrent switches 137, 138, 13% a normally open auxiliaryswitch 141 and a normally closed auxiliary switch 142.

The coil 134 is connected by means of relays hereinafter to be describedbetween the phase 128 of the main circuit breaker 113 and ground.

Referring now to FTGURES 4a, 4b, 5a and 5b power for the operation ofthe controllers and their associated relays and alarms originates in asource of 120 volt A.-C. made available through power lines 293 and 2534of which the line 2654 is grounded or may be an insulated neutral. Atransformer-rectifier 2% supplies 24 volt A.-C. to lines 207 and 268, 24volt D.-C. positive to a line 269, and 24 volt D.-C. negative to a line219. The DC. voltage supplied from the lines 269, 2149 serves toactivate the coils of three-pole double-throw relays 211 to 23sinelusive.

It is a feature of my invention that the relays 211 to 236 are of theinterchangeable plug-in type. I have found that although all the polesare not invariably required such as is the case for the relay 226, itgreatly facilitates the economical operation of my system to utilizerelays which can be replaced by a standard spare and by a simpleplugging in operation. I have also provided my controller with testreceptacles 237 and 238 having contact points 237a23-7k, and 238a-238krespectively.

The left hand pressure device of the unit 94 which is activated by thepressure in the piping shown in FIG. 1 comprises a plurality of switcheswhich operate in response to the pressure of the oil in the piping 96 inpredetermined fashion according to principles that are well known.Accordingly a switch 241 will open when the pressure in the piping 96drops below 250 p.s.i.g. and will close when the pressure rises above250 p.s.i.g.; a switch will open when the pressure in the piping 96drops below 300 p.s.i.g. and will close when it rises above 300 p.s.i.g.A switch 243 (FIG. 4:!) will open when the pressure drops below 260p.s.i.g. and will close when the pressure rises above 260 p.s.i.g.; aswitch 244 will close when the pressure drops below p.s.i.g. and willopen when the pressure rises above 166 p.s.i.g.; a switch 245 (FIG. 55)will close when the pressure drops below 150 p.s.i.g. and will open whenthe pressure rises above 156 p.s.i.g.; and a switch 245 (FIG. So) willclose when the pressure drops below 209 p.s.i.g. and will open when thepressure rises above 200 p.s.i.g., in the piping 95.

Sim larly the right hand device in the unit 9% activated by the pressurein the piping 1G2 comprises an additional plurality of switches whichoperate in response to the pressure of the oil in the piping W2. Aswitch 247 (FIG. 5a) closes when the pressure in "the piping 1% dropsbelow 216 p.s.i.g. and opens when the pressure rises above 210 p.s.i.g.;a switch 248 closes when the pressure drop below p.s.i.g. and opens whenthe pressure rises above 180 p.s.i.g.; a switch 249 closes when thepressure drops below 65 p.s.i.g. and opens when the pressure rises above65 p.s.i.g.; a switch 259 closes when the pressure drops below 45p.s.i.g. and opens when the pressure rises above 45 p.s.i.g.; a switch251 opens when the pressure drops below 60 p.s.i.g. and closes when thepressure rises above 60 p.s.i.g.; a switch 252 opens when the pressuredrops below 75 p.s.i.g. and closes when the pressure rises above 75p.s.i.g.

Gne terminal or" each of the switches 24E through 2.52 is connectedthrough the line 2&9 with 24 volt D.-C. positive. The terminals of theswitches 241 to 246 of the left hand device of the unit 94 are connecteddirectly with the 24 volt line 2% while the switches 247 through 252 areconnected through the relay 223 and a push button 253, which is the oilbutton, to the 24 volt D.-C. line. From this circuit it will be evidentthat pressure on the oil button 253 will deactivate the right handswitches 247 through 252 of the unit 94; similarly energizing the relay223 will deactivate the right hand switches 247 through 252.

The oil pushbutton 253 is a momentary-contact pushbutton which inaddition to the normally closed switch between the 24 volt negativeD.-C. line and the coil of the relay 223 just described has a normallyopen switch between the line 21% and the coil of the relay 225 in serieswith a resistor 254 for which I prefer a value of 100 ohms. The thirdswitch, normally closed, of the pushbutton 253 connects the line 2'39with a blade 256 and a blade 257 of the relay 223.

In addition "to the oil pushbutton 253 I have provided my circuit with anormally open, single-pole, interlock, momentary-contact pushbutton 258connecting the 24 volt negative D.-.line with a red indicator lamp 259and a resistor set which I prefer to have a value of 250 ohms. Asingle-pole, momentary-contact, normally open, cduced pressurepushbutton 262 connects the coil of the relay 2.27 with a blade 263 ofthe relay 226, a blade Zrid of the relay 227 and a terminal 266respectively of I? a relay 225. Another single-pole, momentarymntact,normally open normal pressure pushbutton 26% connects a terminal 269 ofthe relay 223 and a blade 2'71 of the relay 225 with the coil of therelay 225 and with the resistor 254.

A single-pole, normally open, momentary-contact manual controlpushbutton 2'72 connects the positive ll-C. line 269 with "the coil ofthe relay 223. A single pole, normally open, momentary-contact resetpushbutton 273 connects the D.-C. positive line 2% with a blade 2% ofthe relay 235. A double-pole, momentarycontact signal reset pushbu'tton276 comprises a normally open switch between the negative D.-C. lineZltl and the line 2T7 connected as hereinafter described and a normallyclosed switch connecting the positive D.-C. line 2&9 with the line 273connected through diodes i n blades 279, 231, 232, 283, 2%, BS7, f", i 9respectively of the relays Ell, 212, 213, EM, 215, Elle 217, 218, 219and 229. A double-pole, momentar contact, lamp test pushbutton 2&1comprises a normally open switch connecting the 24 volt A.-C. line withthe normally closed terminals associated wit the 351, 353, 3%, 35d, 35?,and 3-5? of the relays 212, 213, 216, 216, 2T7, 21%, 219, respectiv y,aid blades being connected to the red alarm in ,7 3%, Edd, 3th, 3%, 7, 3598 and SW and with the line fill which line is connected withadditional lamps as shall hereinafter be described. The pushbutton 2; Elalso comerises a normally open switch connecting the negative D.-C. line2163 through the resistor Edit, to the red lamp 259 and the coil of therelay 225;.

A timer indicated generally at 311 comprises a motordriven clock 312,solenoid 313 and switches 314, 3 31. timed by the clock 312. For thetimer Ell l prefer to use the type TSA18 catalogue number 695 X 37 DualElectric Cycle Timer made by the General Electric Comparty. Theoperation of the switches 514, 316 and 317 in the timer fill can bevaried to suit the conditions of the system. In one typical installationit prefer to set the timer 311 so that when the solenoid 313 isenergized the switch 31% closes for the full time cycle of 60 minutes,the switch closes for live minutes and then reopens and remains open for"the duration of the cycle and the switch 31? remains open forapproximately five and a half minutes and then closes for the remainderof the cycle. Thus there is a gap of approximately half a minute betweenthe reopening of the switch 314 and the closing of the switch 317. Thelength of the time cycle for the switch 31 should be the experimentallydetermined time required to bring the remote end of the system up topressure.

One terminal of the motor for the clock 512i and one terminal of thesolenoid 313 of the timer 3 11 is connected with the ground wire Theother terminal of the motor for the clock Bill is connected with a therelay 23d, and the other terminal of the solenoid is connected with aterminal 319 of the relay switch Sid connects the positive DC. line withthe coil of the relay 224, the switch 3i"? connects the normal iy openterminal of the blade 31% or" the relay with one terminal of thehigh-voltage coil of a transformerrectifier indicated as 321, and theswitch filo connects the normally open terminal associated with theblade 3T8 of the relay 2% to the normally open terminal associated withthe blade 31) of the same relay.

The transformer-rectifier 321 has its power coil connected across theA.-C. lines 293 and Zlld through the switch 317 of the timer 311. Thetransformer-rectiner 321 supplies 24 volt D.-C. having a common negativethrough the line 21% with the transformer-rectifier The 24 volt D.C.positive output from the transformerrectifier 321 passes through theauxiliary ch of the motor starter (FIG. 3) to the coil of the relay 21 Acapacitor 323 which I prefer to have a rating of 5? Still microfarads,is connected in parallel with tile D.-C. output of thtransformer-rectifier 11a.

A capacitor 324- which I prefer to have a ratin o 508 microfarads oneach of four upper plates has plate connected with the line 27? andopposin 3 connected with blades 3%, 32?, respectively of the relays2-11, 212, 223 and A capacitor 331 for which i prefer to use a unitidentical with the capacitor has one plate connected with the line 2??and op posing plates connected to blades 332i, 333, 334-, 355resgectively oi the relays 215, 236, 217 and A lead (FIG. 3) from thephase 128 of the main circuit breaker 113 furnishes power to the A.-C.line 2% and to the transformer-rectifier 2% through a circuit breaker337 and to a lighting circuit receptacle 339 through a circuit breaker338, and to a chart drive 349 of the unit (H6. 1) through the circuitbreaker 337.

The relays 211, 212, 213, 214, 215, 216, 217, 218, 22%, 222i, 222, 232,233, and 236 all have one side of their coils connected directly withthe ilk-C. negative line Elll. The relay 211 has the other side of itscoil connected through the switch 122 with the ll-C. positive lineZllil, and the red signal lamp Tne blade 341 of the relay 211 isconnected with the A.-C. line 297 and has one terminal connected througha line 342 to a red lamp 343 (MG 5b) and the lamp 299 with the A.-C.line The other terminal of the switch 34-1 of the relayZlll is connectedthrough the line and the green lamp (FlG. 5b) with the 263.

The blade are along with the blades 327, 323, 329, 352, 333, 33% and Mcs5 are connected when their relays are deenergized through a resistorwhich I prefer to have a value of 27 ohms with the ne ative plates ofthe capacitors 32% and The normally open terminals associated with theblade and the blades 327', 32%, 3529, 332, 3533, c334- and are connectedthrough diodes with the positive D-C. line Zlls".

A jumper 3 5-? between the positive side of the coil of the relay 211and the normally open terminal associ-' ated with the blade 279 suppliescurrent to the coil once the relay has been energi d holding the relayclosed until it is released by pressure on the pushbutton 276. Similarjumpers connect the coils and terminals or" the relays 212, 213, 25rd,are, 2171', 218, 219 and The relay 2T2 is energized by the closing dueto high pressure of a switch 34% in the nitrogen pressure alarm 66 (FIG.1). Blades 34%, 3511, 3:32, 353, 354, 556 and 357 respectively of therelays 212, 213, 214, 215, 2 16, 217, 213 are connected through therespective red lamps Edi, 3%, 3%, 3M, 3%, 3% and M7 with the A.-C. line2%. The normally open terminals associated with these blades areconnected to the A.-(). line M7. The relay 213 is energized by theclosing due to low pressure of a switch 358 in the nitrogen pressurealarm The relay 214 is energized by closing of a switch 359 operated bythe oil level alarm 47 when the oil level rises to a preselected levelin the tank 42. The coil of the relay 215 is energized by the closing ofa switch 361 operated by the oil level alarm 47 when the oil level dropsbelow a preselected.

level in the tank 42. The coils of the relays are and 217 arerespectively connected with the switches 24:3 and 24-4 in the left handdevice of the unit 94. A normally closed switch, hereinafter to bedescribed, of the relay 228 is in series with the switch 244. The coilof the relay 218 is energized by the closing of the switch ldll.

One terminal of the coil of the relay 219 is connected through a blade362 and its associated normally closed terminal, of the relay 228withthe negative Tl-C. line lb and the other terminal of the coil isconnected through the normally open terminal associated with the blade2% of the relay 219 and the pushbutton 2'73 with the positive D-C. line269, the normally open terminal associated with the blade 27d of therelay and with the contact 2375 of the receptacle 237, and the control23% of the receptacle 238. The coil of the relay 22% is connectedthrough the switch 364 actuated by the thermostat 49 in the pump room toclose when the temperature in the pump room exceeds a preselected level.Blades 366, 367 of the respective relays 2 19, 229 are connectedrespectively through the red lamps 3%, 34th with the A.-C. line 298. Thenormally open terminals associated with the blades 366, 367 areconnected with the A.-C. line 207.

The coil of the relay 221i is connected between the negative plate ofthe capacitors 32 i and 331 and the negative D.-C. supply line 219. Therelay 221 has blades ass, 369, 371 connected as follows: the blade 36%is connected to the positive D.-C. line 2%, its associated normally openterminal is connected through a resistor 372 which I prefer to have avalue of 100 ohms to the negative plate of the capacitors 324 and 331.The blade 369 is connected with the A.-C. 207 and its associatednormally open terminal is connected across a buzzer switch 373 and abuzzer 374 to the A.-C. line Ziltl. The blade 369 has a parallelconnection with the terminal block 376 to make provision for a remotehell if desired. The blade 271 is connected with the positive D.-C. line2639 and through its associated normally closed terminal and theresistor 377 and diode 3723 with one terminal of the coil of the relay222. The other terminal of the coil of the relay 222 is connected withthe negative DJ. line 210 across the capacitor 37@ for which I prefer arating of 1500 microfarads. I prefer the resistor 377 to have a value of27 ohms. In addition to the before mentioned blade 297 the relay 222 hasa blade 331i and a blade 382. The three blades of the relay 222 areconnected as follows: The blade 297 is connected with the A.-C. line2tl7 and through its associated normally closed terminal and a whitelamp 3% to the A.-C. line Ztlh. The blades 381 and 3552 and theirassociated open and closed terminals are all connected with a terminalblock 333. The terminal block 383 provides terminals 337 through whichconnections can be made to remote alarms.

The receptacle 237 has its contact 23717 connected with the positiveterminals of the coil of the relay 212 and its contact 237i connectedwith the positive terminal or" the coil of the relay 22%. The contact237a is connected to the A.-C. line 2W7, the contact T74! is connectedwith the positive side of the coil of the relay 214 and the contact 2370is connected with the positive side of the coil of the relay 213. Thecontact 237 is connected with the positive terminal of the coil of therelay 216; the contact 237e is connected with the positive terminal ofthe coil of the relay 215 and the contact 237g is connected with thepositive terminal of the coil of the relay 217. The contact 237k isconnected with the A..-C. line 208; the contact 237h is connected withthe positive side of the coil of the relay 218 and the contact 23 isconnected with the positive side or" the coil of the relay 219.

The coil of the relay 223 is connected through the pushbuttons 2'72 and253 between the positive D.-C. line 2&9 and the negative D.-C. line 2MP.The normally open terminal associated with the blade 256 is connected tothe positive side of the coil of the relay 223. The normally closedterminal associated with the blade 257 is connected to the switches 2%,247, 2%, 249, 252, and 251 and to a blade 391 of the relay 224. Thenormally open terminal associated with the blade 257 is connected withthe positive side of the coil of the relay A blade 392 of the relay 223is connected with the A.-C. line 2W7; its associated normally closedterminal is connected with a blade 393 of the relay 225 and itsassociated normally open terminal is connected through an amber lamp 394with the A.-C. line 2% and through a diode or half-wave rectifier 395with the lamp test line 314?. Diode as used in this application isunderstood to refer to half-wave rectifiers which may be any of .aplurality of known types of such rect-ifiers.

The coil of the relay 22- is connected with the switch 248 and 314 onone side and the negative D.-C. line 210 1th on the other. Two of theblades of the relay 224 are utilized. The aforementioned blade 391 isconnected through its associated normally open terminal to a blade 397of the relay 225. A blade 3% is connected with the switch 247 andthrough its associated normally open terminal to the positive side ofthe coil of the relay 224. The relay 225 has its coil connected betweenthe pushbutton ass and through the resistor 254 to a normally openterminal of the pushbutton 253 on one side and to a normally closedterminal of the pushbutton 253 on the other. 0f the three blades 271,397 and 3% of the relay 225 the blade 271 is connected to the pushbutton268 and to the terminal 269 of the relay 225; its associated normallyclosed terminal 255 is connected with the blade 2&3 of the relay 226 andthe blade 26d of the relay 227 and, through the pusnbutton 262, with thecoil of the relay 227; and its normally open terminal with the coil ofthe relay 234 and through a diode 399 to the positive side of the coilof the relay 225. The blade 397 is conneced with the normally openterminal associated with the blade 3% of the relay 224 and itsassociated normally open terminal is connected with the coil of therelay 233. The blade 3-93 is connected with the normally closed terminalassociated with the blade 392 of the relay 22-3, its associated normallyclosed terminal is connected with a blade dill or" the relay 227 and itsassociated normally open terminal is connected with the A.-C. linethrough the amber lamp 48:2 and, through the diode to the lamp test line3%.

The coil of the relay 2126 is connected with the switch 256 on one sideand with the normally open terminal associated with the blade 4- 36 ofthe relay 22-7, and with the coil of the relay 231 on the other. Two ofthe switches of this relay are utilized. These are the switches havingthe blade 263 and a switch having a blade 4nd connected with the blade24% and having a normally open associated terminal connected to thepositive side of the coil of the relay 22s. A normally open terminalassociated with the blade 263 is connected with the positive side of thecoil of the relay .133. The coil of the rela is connected on one side tothe pushbutton 2-152 and on the other to the normally open terminalassociated with the blade 414 of the relay 22%. 0f the blades of therelay 222,? the blade 26d is connected with the pushbutton 262 andthrough its associated normally open terminal with the normally closedterminal associated with a blade 4%? of the relay 229 and to thepositive terminal of the coil 227. The blade 4% is connected through itsassociated normally open terminal with the negative side of the coils ofthe relays 22d and 231; and the blade dial is connected through itsassociated normally closed terminal with the lamp and through the diodeM9 to the lamp test line 32%. Through its associated normally openterminal the blade dill is connected with the lamp 4&5 and with thediode dill which, in turn, is connected with the lamp test line 310.

The coil of the relay 228 is connected on one side with the pushbutton258 and the resistor 261 and on the other side with the blade as"; ofthe relay 229 and with the contact 238a or" the receptacle The blade $62is connected through its associated normally open terminal to the coilof the relay 228. A blade 413 of the relay 228 is connected through theswitch 24-4- with the positive D.-C. line 2%; its associateu normallyclosed terminal is connected to the coil of the relay 217, and itsassociated normally open terminal is connected with the blade 41.5 ofthe relay 22h. A blade 41d of the relay is connected with the negativeD.-C. line 27.6 through the normally closed switch of the pushbutton253; its associated normally closed terminal is connected with thepositive terminal of the coil of the relay 235 and its associatednormally open terminal is connected with the coil of the relay 227.

The coil of the relay 22? is connected on one side through the switch24% with the D.-C. positive line 2439 and to the normally open terminalassociated with the blade 415 of the relay 229, and also to the normallyclosed terminal associated with the contact 233s of the receptacle .38,and on the other side with the D.-C. negative line Zltl. Of the bladesof the relay 2-29 the blade 4W7 is connected as hereinbefore described,a blade ll? is connected through the switch 142 of the motor starter 33(FIG. 3) with the A.-C. line The normally open terminal associated withthe blade 4-17 is connected through the coil or" the magnetic valve 7%with ground.

The relay is a spare relay for which a receptacle is provided having noconnected wiring.

The positive terminal or" the coil of the relay 231 is connected to theswitch 252 and the contact 238 of the receptacle and the negativeterminal is connected to the normally open terminal associated with theblade sec of the relay 2.17. Two of the blades of the relay 231i areoperative. A blade 414.8 is connected with the switch 251 and throughits associated normally open terminal to the coil or" the relay 231; anda blade is connected with the A.-C. line 293. The normally open terminalassociated with the blade 419 is connected through the coil of themagnetic valve 91 with ground.

The coil of the relay 232 is connected between the negative D-C. line26rd on one side and the switch and the contact of the receptacle 233 onthe other. A blade 421 of the relay is connected with the switch 2 :1and its associated normally open terminal is connected to the coil ofthe relay 225;. A blade 422 of the rela 232 is connected with the A.-C.line 2% and the blade 419 of the relay 2.31 and the normally openterminal associated with the blade 422 is connected through the coil ofthe magnetic valve $1 to ground.

The coil of the relay 233 is connector betwee the negative DC line andthe normally open terminals associated with the blades 257, 397 and 2 3resnectively of the relays 223, and 226. A blade of the relay isconnected with the A.-C. line 207; its associated normally closedterminal is lamp with the A.-C. line and through a diode to the lamptestline 3% and its associated normally open terminal is connected tl A.-C.line and thro lamp-test line A blade 4 nected to the A.-C. line openterminal of the lads i connected through the coil and overload switch 31135 of the motor starter 13-3 (HG. 3) with ground. A blade 4531 of therelay is connected with the A.-C. line The normally open terminalssociated with the blade 433 is connected to the blade fill? of therelay 23 The relay is connected between the negative D.-C. line Eli";and the normally ope term nal asso the blade 271 of the reay he bladerelay is connected with the D.-C. line and associated normally openterminal is connected with motor 31?. or" the timer Fill. The blade 31%of the relay 23 is connected through its associated normally openterminal to the solenoid 313 or the timer Slit.

The coil of the relay is connected between normally closed terminalassociated with the blade of the relay on one side; and the switch 245,the normally open terminal associated with the blade 274 of the relay235, and the contact 23% of the receptacle on the other. The blade ofthe relay 235 is cona diode with the a of the relay is con- Theassociated normally nected as has been hereinbeiore described. A blade533 of the relay 235 is connected with the A.-C. line The coil of therelay is connected between the negative lit-Q. line 219 on one and, onthe other side, through jumpers 436, 43"], 433, and in plug-in typeconnectors hereinafter to be described, to the positive D.-C. line andparallel to the said jumpers to the contact of the receptacle 238. Theblade 44?. of the relay is connected through a capacitor which E preferto have a value of 366 microf rads and a resistor which I prefer to havea value of 27 ohms to the normally closed terminal associated with theblade 442. The resistor rd i the capacitor i in parallel are connectedwith the positive t nal of the coil of the relay The normally openterminal associated with the blade 44?. is connected with the positiveD.-C. line A blade of the r lay '2 5 is connected through red lamp 4-36to the A.-C. and through the diode to th lamp-test line 3 Through itsassociated normally closed terminal the blade is connected to is e A.-C.line 235.

ihe contact of the receptacle 238 is connected with the ositive side ofthe coil oi the relay 223, and

i. the cotact is connected with the no live side of the coil of therelay The contact is connected with the positive D.-C. line the contac23% is connected with the positive do of the coil of the relay 22d, andthe coct 2330 is connected with the positive terminal of relay contactis connected with the positive side of the coil of the relay an; thecontact 23552 is connected to the posi. ve side of the coil of the relayand the contact 233g is connected with the positive side of ne coil ofthe relay The contact is connected with the negative DJ. line 211%; thecontact 2- h is C011. ected with po itive side of the coil of relay andthe 2 2 is connected with coil of the relay s the positive side of thecon ccted between the A.--C. lines contact an green lamp i s and andthrough a diode to the lamp-test line 31.

. d512, ir r3, 4-64, 51 to 458 are of commercial sources.

The receptacle 452 the plug toconnected by a cable t'll to a controluanel 47 2 which comprises the push-buttons 291, 2752, 263, 262, 253,253, 273, and and the lamps 3%, $35, 394, 45%, 405, 4%, can, 259, $43,345, .24, 427, 447 and 33%. (FIGS. 4a, 4b). The receptacle 4553 and theplug 4622 together constitute a 24-point connector. The plug isconnected through a cable 473 to a termi block 4%, which is, in turnwired to apparatus comprising the oil level indicator alrrn 47, thepump-room thermostat 4-9, the nitrogen pressure switch The terminalblock 4-74 also provides 8 terminals 4'76 which may be connected toremote alarms if desired.

receptacle and the plug together constitute a 6-point connector. lheplug is connected through a cable 4'77 to a terminal bloclt 378 which,in turn, wired to the normally open magnetic relict valve 7?", thenormally closed magnetic valve to the A.-C. power line (FIG. 3) to thegrounding wire (or insulated neutral) It will be understood thatalthough I prefer to terminate the cables F3 and in the respectiveterminal blocks 4% and 2-78 i do not wish to be limited to thisconstruction and other methods 13 of connecting the plugs 473, 477 totheir control elements either directly or indirectly may be used.

The receptacle 456 and the plug 464 together constitute an 8-pointconnector. The plug 464 being connected through a cable 47? to theterminals of the timer 311.

The receptacle 457 and the plug 466 together constitute a ten-pointconnector. The plug 466 is connected through a cable 421 to a panel 432comprising the switches 122 and 126 of the relay 119 (FIG. 2) the coil134 of the motor starter 133, and the auxiliary switches 141, 142 of thestarter 133 (PEG. 3).

The receptacle 458 and the plug 467 together constitute a 21-pointconnector. The plug 467 is connected through a cable 433 to the panel4-34 for the recorder 94 comprising the switches 241, 24-2, 243, 244,245, 246, 247, 248, 249, 256, 251 and 252 and the chart drive 346.

The jumper 436 in the plug 459 is connected between two points 456 and487 in the connector. Point 467 of the receptacle 451 is connected bymeans of a wire 438 in the panel 443 to a point 489 in the receptacle453. The point 489 is connected by means of the jumper 437 in the plug462 to a point 4% in the connector comprising the plug 462 and thereceptacle 453. The point 491 is connected by means of a wire 492 in thepanel 448 to a point 493 in the receptacle 456. The point 493 isconnected by means of the jumper 438 in the plug 464 to a point 494 inthe plug 464. The point 494 is connected my means of a wire 4% in thepanel 4-48 to a point 497 in the receptacle 457. The point 497 isconnected by means of the jumper 439 in the plug 466 to a point 4% inthe plug 466. The point 4% is connected by means of a wire 499 in thepanel 443 to a point 561 in the receptacle 453. The point 561 isconnected through the jumper 441 in the plug 467 to a point 562 in theplug 467. The jumpers 436, 437, 438, 439, 441 and panel Wires 483, 4-924%, 499 are thus seen to form a series connection between the point 486and the point 562 which will be interrupted by the separation of any oneor more of the plugs 45%, 462, 464, 466, or 467 from its matingreceptacle.

I have hereinbefore indicated that I prefer to use standard plug-in type3-pole, double-throw relays for the relay panel or" my controller 11. Ihave found that although a plurality of said relays do not require theuse of all the terminals of the 3-pole, double-throw type the advantagesof standardization outweigh any hypothetical economy that might beachieved by using simpler types of relays where they would sulfice. Oneadvantage, which will be immediately apparent, is that the spare relay236 may be quickly substituted for any of the other relays thatmalfunctions or becomes damaged. 1 have preferred to use ll-pin relayshaving S-ampere contacts and a 24- volt D.-C., 475 ohm coil such as therelays made by the Line Electric Company and sold under their number MKP31934. The operation of the said relays is independent ,of the polarityof the coil connections.

I have provided two ll-point test receptacles 237 and 23-8. Thereceptacles 237 and 233 are not intended for the insertion of relays butfor the insertion respectively of an 11-point jack 661 having pins661a601k and an 11- point jack 632 having pins 6tl2a-6tl2k (FIGS. 7 and8), said jacks comprising part of a test unit designated generally as 663. The jacks 691 and 662 are connected to the test unit 663 by theirrespective cables 604 and 666. The cables 664 and 666 enter a housing667 upon which are mounted a D.-C. voltmeter 668 and its associatedpush-button 669, an A.-C. voltmeter 611 and its associated push-button612, a relay test receptacle 613 having contacts 61342-613k, and itsassociated push-button 614, red lamps 616, 617, 618 and green lamps 619,621, 622. Also mounted on the housing 667 are a plurality of pushbuttons623, 624, 626, 627, 623, 6.29, 631, 632, 633, 634, 636, 637, 638, 639,641, 642, 643, each having one terminal connected through the cable 666to the pin 662a of the jack The remaining terminals of the pushbuttonare connected to the pins of the jacks 661 and 662 as follows: 623 isconnected to 6011b; 624 is connected to 6010; 626 is connected to 661d;627 is connected to tlle; 628 is connected to 691 629 is connected to601g; 631 is connected to 66%; 632 is connected to 661i; 633 isconnected to 661 634 is connected to 602k; 636 is connected to 6620; 637is connected to 602d; 638 is connected. to 662a; 639 is connected to662;; 641 is connected to 662g; 642 is connected to 6tl2h; 643 isconnected to 692:. The pushbutton 6'69 is connected between the pin 692aand the D.-C. voltmeter 663 and thence to the pin 662k. The pushbutton612 has one terminal connected to the pin 691a and also to the contacts613a, 613k and 613 and the other terminal connected through the A.-C.voltmeter 611 to the pin 601k and each of the lamps 616, 617, 618, 619,621 and 622.

The relay test push-button 614- is connected between the pin 662a andthe contact 61312. Each of the lamps is connected to a contact of thetest receptacle 613 as follows: 616 is connected to 613d; 617 isconnected to 613a; 618 is connected to 61312; 619 is connected to 6130;621 is connected to 613g; 622 is connected to 6131'.

The jack 662 plugs into the receptacle 238, each of the pins of the jackfitting into a like lettered contact of the receptacle. Similarly thejack 601 plugs into the receptacle 237, each of the pins again fittinginto the contact having the same letter designation. The relays 212-236, being identical, will each fit the receptacle 613 in such a mannerthat when a relay is inserted the contacts 61% and 6l3j will be acrossthe coil, 613a will contact one blade, 6130 will contact the normallyopen terminal associated with the blade contacted by 613a, and 613d willcontact the normally closed terminal associated with said blade. Thecontact 613 will connect to another of the blades of the relay, 613g tothe normally open terminal associated with said blade and 613e to thenormally closed terminal associated with said blade. The contact 613kwill connect with the third blade of the relay, 613i with the normallyopen terminal associated with said blade and 613/2 with the normallyclosed terminal associated with said blade.

Operation To introduce oil into a newly installed pipe-type cable theentire system is first flushed out with dry nitrogen. A vacuum pump maythen be connected to the system by means of the normally closed manualvalve 761 (FIG. 1). I prefer to evacuate the entire system to a pressureof 1 mm. or less of mercury and to search out and repair any leaks untilthe system will show an increase of pressure less than 1 mm. of mercuryin one hour. Oil is then introduced into the system while stillmaintaining vacuum at the valve 761 until oil passes through the valve.The oil storage tank 42 has a volume adequate for the volumefluctuations of the system in operation but insufficient to fill thesystem initially. I have therefore provided a normally closed manualauxiliary filling valve 702 through which the system can be filleddirectly from tank trucks. During the filling the pump 13 may bebypassed. If the pump 13 is operated to fill the pipe-.ype cable thecontrols may be set for manual or reduced pressure operation during thefilling operation. During reduced pressure operation the pump will stopwhen the pressure reaches a value which I prefer to set at 65 p.s.i.g.

With the system still under vacuum and the valves 41 and 46 open, oilwill enter the oil storage tank 42. When a sulficient supply of oil hasentered the tank 42 leaving enough volume in the tank to accommodate theoil that will be forced from the pipe-type cable when the latter isenergized with a consequent increase in temperature the valve 46 (and46a for a 2-controller system) is closed and the remainder of the tank42 filled with dry nitrogen from the cylinder 50.

The system having been filled with oil the valves 761 and 762 areclosed, the valve 46 (and 46a) opened and the system maintained atreduced pressure until the cable system is ready to be tested and/ orenergized. When the system is ready to go from reduced pressure ontonormal pressure operation it is only necessary to depress the normalpressure push-button 268 (FIG. a) momentarily energizing the coil of therelay 225. Energizing of the coil or" the relay 225' will move the blade271 to its normally open terminal and continue to feed current to thecoil so long as the blade 256 of the relay 223 is in its normally closedposition. If, however, the manual pushbutton 272 has been depressed andthe relay 223 is locked in its energized position no current will feedinto the blade 271. In this situation it is first necessary to depressthe oil push-button 253 and open the circuit supplying current to theblade 25d of the relay 223 so as to deenergize the coil of that relay.When the system is in normal condition with the relay 225 energized, theblade 393 will have closed the circuit to light the amber lamp 4 62.Consider the case where the system is in normal operation there isadequate pressure in the pipe-type cable and the pump is not running.The coil 134 (FIGS. 3 and 5b) of the motor starter 133 will bedeenergized. When, because of a decrease in the ambient tern aerature orin the load in the cable the oil cools somewhat and the pressure in thepiping (FIG. 1) drops below 200 p.s.i.g. the switch 246 in the unit Mwill close energizing the coil of the relay Z29 whereby the blade 4-17will move to its normally open terminal and close the magnetic reliefvalve '79 so long as the pump is inoperative. When the coil 1% for themotor starter 133 is energized the auxiliary switch 142 will open thecircuit through the magnetic valve 7 9. Closing of the valve '79 willprevent any oil from leaving the pipetype cable and returning to thestorage tank 42. As cooling continues and the pressure in the line 96drops to 180 p.s.i.g. the switch 248 will close and energize the coil ofthe relay 224 (so long as the relay 223 which is responsive to themanual push-button 27?. is in its deenergized position). Under theseconditions the switch 247 which closes at a pressure of 210 p.s.i.g.will be closed locking the relay untilthe pressure rises above 210p.s.i.g. With the coil of the relay 22d energized the blade 391 will bein contact with its normally open terminal and current will pass fromthe positive D.-C. line 2% through the push-button 253, the blade 257 ofthe relay 223, the blade 391, the blade 3%7 of the relay 225 which isenergized when the system is at normal pressure operation, to energizethe coil of the relay 23-3 thus moving the blade .29 to close thecircuit through the motor starter coil 134, starting the pump 13. At thesame time the blade 423 will move to extinguish the green lamp 424 andlight the green lamp 42'3".

During normal pressure operation the coil of the relay 234 will beenergized through the blade 271 of the relay 225. The blades 318 and 319of the relay 23:4 will be in contact with their respective normally openterminals in the circuits supplying current to the motor 3l2 andsolenoid 313 of the timer Ell-ll.

The blade 313 is connected to the A.-C. line 2% so that when the systemis in normal pressure operation resulting in the relay 234 beingenergized the clock motor ElZ of the timer 311 will be in operation. Theblade 31% is connected to the normally open terminal of the blade 431 ofthe relay 233 so that when the pump starts during normal operation thesolenoid 3ll3 will start a time cycle. Since the relay 234 is notenergized during manual and reduced pressure operation the timer willnot start under those conditions even though the pump is activated. Ashas been hereinbefore stated, when a time cycle starts the switch 314will close for a period (typically 5 minutes) sufficient for pressure toreach the remote end of the pipetype cable. The switch 314 bypasses theswitch 248 energizing the coil of the relay 224 for a five-minute periodeven though the switch 247 should open due to the pressure in the piping96 exceeding a value of 210 p.s.i.g. Adequate pressure is thus assuredthroughout the entire length of the system. At the termination ofaperiod which ll prefer shall. be minute after the reopening of the lbswitch 314 the timer 311 will automatically close the switch 317 in theprimary circuit of the transformer-rectifier 321i (HG. 45). If, at orduring the time the switch 317 is closed, both the relays 233 and 234are energized (indicating that the pump is operating under normalpressure conditions) and the auxiliary switch l t-ll (FIG. 3) of themotor starter 133 is closed the transforr er-rectifier 3211 will energie the relay are, lig ting the red lamp through the blade 35? and throughthe'blade 355 energizing the coil of the relay 221 (H6. 45) which closesthe circuits to optional remote alarms connected to the terminal block383. Since the switch 317 of the timer 311 will remain closed for achosen period such as 4 /2 minutes starting of the pump due to loss ofpressure during this period will cause an excessive cycling signal. Bythis means I am able to give an alarm for slow leaks which are notsufiicient to cause a drop in pressure exceeding the capacity of thepump. The timer Ell can be reset manually at any time during any part ofits cycle by depressing the off push-button 253 followed by depressingthe normal pressure pushbutton 26%. Since an alarm will be given if thepump is operating under normal operation condition at the same time asthe timer switch 317 is closed, my method of wiring will provide awarning for both the case where the pump requires excessive time tobring the system up to pressure, and the case where the pump restartstoo soon after having brought the system to pressure. This latterwarning will be given by virtue of the fact, heretofore noted, that theswitch 317 will remain closed for 60 minutes from the time the pump isstarted.

Should the pressure drop to p.s.i.g. in the line 9d the witch 244 willclose connecting the lade 42 5 of the relay with the positive D.-C. line2&9. if the system is operating at reduced pressure the coil of therelay 223 will be energized and the blade will be in electricalconnection with the blade 415 of the relay 2 29 and closure of theswitch 244 will have no effect except as a second source of current tokeep the coil of the relay Z2) energized. Under normal pressureoperation, however, the relay 223 will be deenergized and the blade 413will be connected with the coil of the relay 2E7. Closing of the switch24 under normal pressure conditions will thus energize the relay 217,lighting the red lamp by means of the blade see and energizing the coilof the relay 221 by means of the blade 3% and capacitor The relay 221will sound a buzzer 3'74 and energize the terminal block 376 which maybe connected with a remote hell or bells and will also deenergize thecoil of the relay 2Z2 lighting the white lamps 325% and, by means of theblades 331 and sea, activating the remote alarms connected to theterminal block 383.

When, instead of a loss of pressure, the pressure in the pipe-type cablerises due to an increase in temper ture at a time when the system is innormal pressure operation the valve 79 will open due to opening of theswitch 246 and the relay 229 when the pressure reaches 200 p.s.i.g.; thepump will stop due to opening the switch 247 and deenergizing the relays22d and 233 when the pressure reaches 210 p.s.i.g. provided it has notbeen stopped already by the timer 311i. When the pressure rises to 225p.s.i.g. the mechanical relief valve 8i will open and oil will then flowbaclr into the tank 32 through the pipe 14, valve to, cross coupling 18,valve 17, T 2d, union 22, valve 27, pipe 26, Ts 73, 74, in, '77,strainer 78, valves '79, 81 and 82, Ts 83, 8 8d, valve 87, union 21,pipe 38, valve 41, T 4-3 and the valve 45. When the pressure reaches 250p.s.i.g. the valve 88 will open providing a parallel return through thevalve 39 and the switch 241 will close. At 260 p.s.i.g. the switch 243(FIG. 4a) will close energizing the coil of the relay 216 which willlight the red lamp 3&5 and through the relays 221 and 222 ashereinbefore described, sound the buzzer 374 and the remote alarms andlight the lamp 3%. If the pressure continues to rise to 300 p.s.i.g. theswitch 242 will close, energizing the coil of the relay 232 which willremain energized until the switch 241 opens again at 250 p.s.i.g. Therelay 232 will open the valve 91 by means of the blade 422. This willprovide another parallel oil channel through the check valve 92 andvalve 93 for the return of oil to the tank 42. Finally the safety valve95 in the pump 13 will relieve at 375 p.s.i.g., and should the reservoir42 start to build up pressure, a safety disk 703 therein will rupture ata pressure of 60 p.s.1.g.

A feature accounting in part for the close limits within which I am ableto maintain the oil pressure on a pipetype cable system resides in therelationship of the valves 81, 79 and 88 of which, as has been describedheretofore, the valve 31 is a mechanical valve which opens into thevalve 32 when the pressure behind it exceeds 225 p.s.i.g., the valve 88is a mechanical valve which opens into the valve 89 when the pressurebehind it exceeds 250 p.s.i.g. and the valve 79 is a magnetic valveoperated by means of the switch 24s and the relay 229 to close when thepressure drops below 200 p.s.i.g. Of the manual valves 91), 82 and 89the valves 82 and 39 are normally open and the valve 9% is normallyclosed. Under normal pressure operation no oil will pass through thevalve system comprising the valves 81, 79 and 88 until the pressure hasbuilt up to 225 p.s.i.g. At this point the valve 81 will open relievingthe pressure in the line in a manner that has already been described.Since oil is practically an incompressible medium the pressure will dropvery quickly when the valve 31 opens and I have found that although,ideally, the valve 31 should close again as soon as the pressure dropsbelow 225 p.s.i.g. actual commercial mechanical relief valves have aconsiderable time lag before they seat properly. I have found thisparticularly to be the case when there was a considerable flow of oilthrough them.

In the instance case, however, as soon as the pressure drops to 200p.s.i.g. the magnetic valve 79 closes and permits the mechanical valve81 to lock into place. The valve 83 provides a safety relief which willopen in the event of malfunctioning that closes the valve 79 or fails toopen the valve 31 even at elevated pressure.

In the event that the temperature should rise excessively in the pumproom the switch 364 in the thermostat 49 (FIG. 1) will close, energizingthe coil of the relay 22% and lighting the red lamp 311%. A high-lowcontrol 47 on the reservoir 12 comprises the switches 35? and 351.Should the oil level drop too low the switch 361 will close energizingthe relay 215 to light the red lamp 3114 and energize the relay 221 tolight the white lamp 3% and sound the buzzer 3'74 and the remote alarms.A high oil level will act similarly through the switch 352 and the relay214 except that it will light the red lamp 3113. The nitrogen control ashas switches 3 18 and 353. Should the pressure drop below a selectedvalue such as 2 p.s.i.g. the switch 358 will close and energize the coilof the relay 213 lighting the red lamp 302. Should the pressure riseabove some value such as p.s.i.g., the switch 348 will close to energizethe relay 212 and light the red lamp 391. In either event the relay 221will be energized, lighting the white lamp 381) and sounding the buzzer374 and the remote alarms.

I prefer to have two independent 3-phase sources of power supply, anormaly supply 111 (FIG. 2) and an emergency supply 112. The powertransfer switches 114 and 117 for these sources. are mechanicallyinterlocked by a mechanism 115 of known construction for which I make noclaim of invention. The mechanism 115 is so constructed that either orboth of the circuit breakers 114 and 117 may be open simultaneously;either the circuit breaker 114 of the circuit breaker 117 may be closed;but both the circuit breakers 114 and 117 cannot be closedsimultaneously. If there is power in the normal supply 111 current willflow from the phases 127 and 128 to energize the coil 121 of the relay119 closing the switches 124 and 126 and opening the switches 122 and123. With the switch 124 closed the relay 116 will be energized to closethe switch 114 supplying current to the lines 113. In the event offailure of the normal source 111 the coil 121 will be deenergized andthe switches 124 and 126 will open and the switches 122 and 123 willclose. Closing of the switch 123 will energize the coil 118 of thecircuit breaker 117 from the phases 131 and 132 thus closing the switch117 to supply the power lines 113. Return of power to the source 111will energize the coil 121 thus closing the switch 114. Due to themechanized interlock the switch 117 will then open.

When, due to loss of power at the source 111 the switch 122 closes andenergizes the coil of the relay 211 (FIG. 4a) (note that in FIG. 4a therelay 211 is deenergized even though the switch 122 is closed; this isdue to the fact that the condition of the system in the drawings is onewhere the entire system is deenergized) the relay 211 will light the redlamps 229 and 343 and energize the coil of the relay 221 to sound thebuzzer and give the remote alarms. Each of the alarm relays 211, 212,213, 21 i, 215, 216, 217 and 218 looks in its closed position by meansof current received through the right hand contact of the signal resetpushbutton 276 and will be deenergized when the pushbotton 276 isdepressed. Depression of the pushbutton 276 will also, through its lefthand contact, discharge the capacitors 324 and 331 and deenergize therelay 221. It is a feature of my invention that the coil of the relay222 is connected in parallel with the capacitor 379 and in series withthe resistor 377. Due to a finite length of time, which is about 5seconds using my preferred components, required to discharge thecapacitor, the relay 222 will remain energized during momentary currentinterruptions and will not give a remote alarm. If this delay featurewere omitted from my invention a trouble-shooter might journey aconsiderable distance to the controller from a remote alarm stationunnecessarily.

When the system utilizes both the controllers 11 and 11a I have foundthat it is convenient to have the normal power supply 111 for thecontroller 11 constitute the emergency power supply for the controller11a and to have the emergency power supply 112 for the controller 11constitute the normal power supply for the controller 11a. In thismanner both power sources will be utilized during normal operation andwill be kept under the surveillance of the alarm system and yet thesystem will have the safeguard of a secondary power source. When twocontrollers are utilized either pump can be made to supply pressure forthe alternate side of the system by means of the normally closedmagnetic crossover valves 33 and 34. Consider the controller 11 with theunderstanding that an analogous discussion will apply to the controller11a. Should the pressure in the system, as reflected by the pressure inthe piping 96, drop to p.s.i.g. the switch 245 in the recorder 94 willclose, energizing the coil of the relay 235 to I light the amber lamp 4%and open the magnetic valve 3. With the valve 33 open oil will flow fromthe union 23a through the valves 37, 33, 31 and 35 into the low pressuresystem. When the pressure in the piping 192a is reduced to p.s.i.g. thepump 13a will start in a manner analogous to that hereinbefore describedfor starting the pump 13. In order for the relay 235 to remain energizedcurrent must be supplied to the line connected to the normally openterminal associated with the blade 274. Such current will be receivedthrough the blade 23% of the relay 219 when that relay is energized. Therelay 212 is energized at the same time as the relay 235 when the switch245 closes provided the relay 223 which is energized during reducedpressure operation is in the deenergized condition with its blade 352 inits normally closed position. This interlock of relays prevents oil fromdraining from the controller 11a to the controller 11 when the latter isoperating at reduced pressure. When the relay 21% is energized byclosure of the switch 24$ the red lamp 311% will be lighted by means ofthe blade gize the coil of the relay 231.

When there is a leak in the pipe-type cable system sufficiently large torequire deenergizing of the cable system it is desirable to reduce theoil pressure in the system to reduce oil losses through the lealrr Thepressure in the line can be reduced by depressing the oil pushbutton253, and then simultaneously depressing the reduced pressure interlockpushbutton 258 and the reduced pressure pushbutton 2'52. vides a safetymeasure so that only a person who is familiar with the proper sequencewill be capable of putting the pump on reduced pressure. Depressing theoff pushbutton 253 when the system is operating at normal pressure willbreak the circuit to the coil of the relay 225 which has hereinbeforebeen shown to control the normal pressure operation in responseto thepushbutton 25 3.

This required sequence pro- As a further precaution, when the oilpushbutton 253 is depressed the positive terminal of the coil of therelay 225 is connected throughthe resistor 254; to the negative D.-C.line 21a. Subsequent depression of the reduced pressure interlockpushbutton 253 will close the circuit to the coil of the relay 223provided the relay 22a is energized which will be the case whenever thepressure has dropped to 200 p.s.i.g. due to the action of the switch 246as hereinbefore described. Should the relay 229 be deenergized, thecircuit to the coil of the relay 223 instead of passing to the bladedirectly from the positive D.-C. line M99 will follow the circuit formedby the blade ull, the normally open terminal associated with the blade2:54 or" the relay 227, the pus button ass, the terminal 266 and blade271 of the relay 225, the terminal 269 and blade 25d of the relay 223, anormally closed contact of the pushbutton 253 and the E.-C. line 269.Simultaneous depression of the pushbuttons 253 and 262 will haveenergized' the coil of the relay 227 which through the means of theblade 4% will energize the coil of the relay 231 and open the magneticrelief valve 91 (FIGS. 1 and 5b) by means of the blade With the valve 91open the oil pressure will quickly drop to 200 p.s.i.g. at which pointthe valve 2% will close, as hereinbefore described, to energize therelay 22% and connect the blade t'll? directly to the DJ. line 299.While the system is operating at reduced pressure the coil of the relay233 controlling the pump motor will be in the circuit including theblade 263 of the relay 226 which will start the pump when the pressuredrops to 4-5 p,s.i.g. closing the switch 256' and stop the pump when thepressure increases to 65 p.s.i.g. Once the system is operating regularlyat reduced pressure the valve 91 will close under 7 the influence of theswitch 251 acting through the relay 231 when the pressure drops to 60p.s.i.g. and remain closed, unless for some reason such as an increasein oil temperature, the pressure should rise to 75 p.s.i.g. under whichcircumstance the switch 252 would close and ener While the controller llis operating under reduced pressure the blade 41d of the relay 21-3 willopen the circuit to the coil of the relay Z35 controlling the valve 33thus assuring that the valve 33 will remain closed and not drain oilfrom the controller Ma. The blade 413 of the relay 228 will also haveopened the circuit of the coil to the relay 217 so that no remote alarmwill be given due to closing of the oil pressure alarm switch 244.

As a safety measure preventing the inadvertent return to normal pressureI have provided that it shall be necessary to push the manual pushbutton2'72 to return the system from reduced pressure to normal pressureoperation. The manual pushbutton 2'72 operates as follows: Depression ofthe manual pushbutton 272 energizes the coil of the relay 223 whichautomatically locks in by means of the blade 256. With the relay 223energized the normal pressure pushbutton 263 and the reduced pressurepushbutton 2.62 will be inoperative since they are in a series circuitwith the normally closed terminal 269 of the blade 256. The switches248, 247, 25%, 249, 252, 251 are all connected through the normallyclosed termi- 2h nal associated with the blade 25? to the line 2G9 andare inoperative when the blade 257 is connected to its normally openterminal. When the relay 223 is energized the blade 257 will connectwith the coil of the relay 253 starting the pump '13. Movement of theblade 392 when the relay 223 is energized serves to extinguish the redlamp 4% and light the amber lamp With the pump 7 13 operating undermanual control the pressure will build up to 200 p.s.i.g. at which pointthe switch 246 will open and deenergize the relay 2239. The blade ill?will then move to its normally closed position but with the blade inthis position the circuit to the coil of the relay will be still openbecause t 1is circuit includes the blade 25% and terminal 269 of therelay 2Z3.

is a feature of my invention that the lamps can all be tested at once bythe simple depression of a pushbutton without interrupting normaloperation or setting oif any false alarms. For this purpose I haveprovided a lamp test pushbutton 231 connected to the A.-C. line Ztl7.The lamps 21%, Sill, 3%, 3M, ans, 34W, 36155, are each connected to ablade of a relay each of which blades has one associated terminalconnected with the lamp test pushbutton 2M and its other associatedterminal connected directly to the A.-C. supply. Thus when thepushbutton 2% is depressed all the above mentioned lamps should be liteither directly or through the pushbutton. The remainder of the panellamps with the exception of the red lamp 259 are connected throughindividual diodes that prevent the AC. current, used to supply any onelamp during normal operation, from light ing any of the others throughthe test circuit. The red lamp 259 is connected through the pushbutton291 between the negative D.-C. line and the positive D.-C.

line 2%.

it is an advantage of my invention that the lamps associated with mycontrol circuit, such. as the lamp 3%, can be tested by the depressionof the pushbutton ZJl but are not affected by the current feeding intoother lamps on the same circuit. In the case or" the lamp 3%, forexample, the lamp 4432 might be lighted by the energizing of the relay225 whereby the blade 3% would close the circuit comprising the A.-C.2&7, the blade 3% of tae relay 21213, the blade of the relay 225, thelamp and the A.-C. line 283, without lighting the lamp because of thediodes and 4 93.

l have provided that in the event of a complete power outage involvingboth the normal and emergency power sources the system willautomatically return to normal pressure operation when power is restoredprovided it was operating at normal pressure at the time of the powerinterruption. l accomplish this objective in the following manner: Thepositive terminal of the coil of the relay 225' is connected to oneplate of the capacitor When power is resumed the relay 236 is energizedand the blade 4-42 becomes connects to the positive D.-Ci line. Currentcan then pass through the coil of the relay 225 to charge the condenser4-43 thereby energizing the coil 2% in a manner analogous to depressingthe normal pressure pushbutton 268.

An important novel feature of'my invention is provided by the testreceptacles 237 and 238 and the test unit 6&7 (FIGS. 7 and 8). Themethod of operating this unit .is as follows: The jack 6% is inserted inthe receptacle 237 and the jack 6% is inserted in the receptacle 238.The test button 612 is then depressed with the result that the A.-C.voltmeter all will indicate the voltage across the low voltage A-C.lines 2597 and 2%. The test button sea is then depressed to indicate onthe D.-C. voltmeter 6% the voltage across the D.-C. lines 2% and Zltl.

When the jack 62 is inserted in the receptacle 23.3 the jumper 6% servesto short the positive lead to the coil of the relay 222 to the positiveline 269 thus keeping 21 With the jacks 601 and see inserted depressionof the pushbutton 623 will energize the coil to the relay 2E2 and, ifsaid relay and its associated circuit is operating properly, light thelamp 3%. The relay 212 should then be deenergized by depressing thesignal reset pushbutton 276. Similarly, depression of the pushbuttons62d, 6%, 627, 628, 629, 631, 632 and 633 will test the.

relays 213, 214, 215, 216, 217, 218, 219 and 2 2th and their associatedcircuits, by respectively lighting the lamps SM, 393, 304, 305, fetid,3M, 3% and 3%. The relay 223 and its associated circuit is tested bydepressing the pushbutton 634 to light the lamp 394. To test the relays224 and 225 and their associated circuitry, the pushbutton 263 is firstdepressed, following which, depression of the pushbutton 636 will startthe pump motor. The relays 226, 227 and 228 and their associatedcircuits are tested by depressing the reduced pressure interlockpushbutton 258 and the reduced pressure pushbutton 252 following which,depression of the pushbutton 637 will start the motor. It will beunderstood that in testing the relays 2123, 224, 225, 2-26, 227 and222'; it is first necessary to depress the off pushbutton 253 to clearthe controls. Prior to testing the relays 226 or 231 the valve 17 shouldbe closed to prevent loss of pressure in the system while the cable isenergized. The relay 229 and the valve iii and their associatedcircuitry are tested by depressing the pushbutton (:33 which has theeffect of seating the valve. The relay 232i and the valve 91 and theirassociated circuitry are tested by depressing the push'outton 63%, andsimilarly the relay 232 will close the valve 91 when the pushbutton 641is depressed. The relay 235 and the valve 33 and their associatedcircuits are tested by depressing the pushhutton 6 52. To test the relay236 and its associated circuit by lighting the lamp 3%, the plug 45dshould be removed from the receptacle 451 following which the pushbuttons43 should be depressed. All the relays can be further tested byinserting them in the test receptacle 613. When a relay is inserted inthe receptacle 633, A.- C. current is supplied to each of the threeblades of the relay through the contacts 613a, 613k and 6133f and thelamps 616, 617, 613 which are connected to the normally closed terminalswill light. Whenthe relay test button 614 is depressed D.-C. voltagewill be impressed across the coil of the relay being tested through thecontacts 613!) and 633j, moving the blades to light the lamps 619, 621,622 and extinguish the lampsei, i517 and 618.

I claim:

1. Apparatus for controlling oil pressure in an electric cablecomprising an oil reservoir, piping connecting said reservoir with saidcable, a pump delivering oil from said reservoir into said cable, aplurality of sets of pressure sensing devices, responsive to thepressure of the oil in said cable, a first of said sets of pressuresensing devices responsive to a first selected range of pressures, asecond of said sets of pressure sensing devices responsive to a secondselected range of pressures lower than said first range of pressures, afirstautomatic means for starting and stopping said pump and thusmaintaining said cable within said first range of pressures in responseto the first of said sets of pressure sensing devices, a second meansfor starting and stopping said pump and thus maintaining said cablewithin said second range of pressures in response to the second of saidsets of pressure sensing devices, manual means for transferring theoperation of said pump from said first means for starting and stoppingsaid pump to said second means for starting and stopping said pump, saidmanual means comprising a plurality of manually operated units operativein only one of a plurality of possible manual sequences.

2. Apparatus for controlling oil pressure in an electric cablecomprising an oil reservoir, piping connecting said reservoir with saidcable, a pump delivering oil from said reservoir into said cable, aplurality of sets of pressure sensing devices responsive to the pressureof the oil in said cable, a first of said sets of pressure sensingdevices responsive to a first selected range of pressures, a second ofsaid sets of pressure sensing devices responsive to a econd selectedrange of pressures lower than said first range of pressures, at firstautomatic means for starting and stopping said pump and thus maintainingsaid cable within said first range of pressures in response to the firstof said sets of pressure sensing devices, a second means for startingand stopping said pump and thus maintaining said cable within saidsecond range of pressures in response to the second of said sets ofpressure sensing devices, manual means for transferring the operation ofsaid pump from said first means for starting and stopping said pump tosaid second means for starting and stopping said pump, said manual meanscomprising a plurality of manually operated units operative in only oneof a plurality of possible manual sequences, hand operated means forstarting and stopping said pump, means for disengaging said pump fromsaid first and said second starting and stopping means and making saidpump responsive to said hand-operated starting and stop plug means,manual means for disengaging said pump from said hand-operated startingand stopping means and making said pump responsive to said firststarting and stopping means, said manual means for disengagingcomprising a plurality of manually operative units operable in only oneof a plurality of possible manual sequences.

3. Apparatus for controlling oil pressure in an electric cablecomprising an oil reservoir, piping connecting said reservoir with saidcable, a pump delivering oil from said reservoir into said cable, aplurality of sets of pressure sensing devices responsive to the pressureof the oil in said cable, a first of said sets of pressure sensingdevices responsive to a first selected range of oil pressures, a secondof said sets of pressure sensing devices responsive to a second selectedrange or" oil pressures lower than said first range of oil pressures, afirst automatic means for starting and stopping said pump and thusmaintaining said cable within said first range of pressures in responseto the first of said sets of pressure sensing devices, a secondautomatic means for starting and stopping said pump and thus maintainingsaid cable within said second range of pressures in response to thesecond of said sets of pressure sensing devices, manual means forstarting and stopping said pump, an electric power source supplying saidapparatus, automatic means whereby, after an interruption of said powersource and following the resumption of said power source said pump willbe operative in response to the first of said starting and stoppingmeans.

4. Apparatus for controlling the oil pressure in an electric cablehaving a first cable length and a second cable length comprising a firstpump normally delivering oil to said first cable length, a normal set ofpressure sensing devices responsive to the pressure of oil in said firstcable length, a supplementary set of pressure sensing devices responsiveto the pressure of oil in said first cable length, said supplementaryset of pressure sensing devices being responsive to lower pressures thansaid normal set of pressure sensing devices, said pump being responsiveto said pressure sensing devices, a second pump normally delivering oilto said second cable length, automatic means constraining said secondpump to deliver oil to said first cable length when the oil pressure insaid first cable length drops below some preselected value andpreventing said second pump from delivering oil to said first cablelength before the oil pressure in said first cable length has dropped tosaid preselected value, said automatic means being operative when saidfirst pump is responsive to said normal set of pressure sensing devicesand being inoperative when said first pump is responsive to saidsupplementary set of pressure sensing devices.

5. Apparatus for controlling the oil pressure in an electric cablehaving a first cable length and a second cable

1. APPARATUS FOR CONTROLLING OIL PRESSURE IN AN ELECTRIC CABLECOMPRISING AN OIL RESERVOIR, PIPING CONNECTING SAID RESERVOIR WITH SAIDCABLE, A PUMP DELIVERING OIL FROM SAID RESERVOIR INTO SAID CABLE, APLURALITY OF SETS OF PRESSURE SENSING DEVICES, RESPONSIVE TO THEPRESSURE OF THE OIL IN SAID CABLE, A FIRST OF SAID SETS OF PRESSURESENSING DEVICES RESPONSIVE TO A FIRST SELECTED RANGE OF PRESSURES, ASECOND OF SAID SETS OF PRESSURE SENSING DEVICES RESPONSIVE TO A SECONDSELECTED RANGE OF PRESSURES LOWER THAN SAID FIRST RANGE OF PRESSURES, AFIRST AUTOMATIC MEANS FOR STARTING AND STOPPING SAID PUMP AND THUSMAINTAINING SAID CABLE WITHIN SAID FIRST RANGE OF PRESSURES IN RESPONSETO THE FIRST OF SAID SETS OF PRESSURE SENSING DEVICES, A SECOND MEANSFOR STARTING AND STOPPING SAID PUMP AND THUS MAINTAINING SAID CABLEWITHIN SAID SECOND RANGE OF PRESSURES IN RESPONSE TO THE SECOND OF SAIDSETS OF PRESSURE SENSING DEVICES, MANUAL MEANS FOR TRANSFERRING THEOPERATION OF SAID PUMP FROM SAID FIRST MEANS FOR STARTING AND STOPPINGSAID PUMP TO SAID SECOND MEANS FOR STARTING AND STOPPING SAID PUMP, SAIDMANUAL MEANS COMPRISING A PLURALITY OF MANUALLY OPERATED UNITS OPERATIVEIN ONLY ONE OF A PLURALITY OF POSSIBLE MANUAL SEQUENCES.